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# Create a list of names
names = ["Ripley", "McClane", "Ryerson", "Murphy"]
# group by first letter
names_by_letter = names.group_by { |name| name[0] }
#{
# "R" => [
# [0] "Ripley",
# [1] "Ryerson"
# ],
# "M" => [
# [0] "McClane",
# [1] "Murphy"
# ]
#}